Chuck

ABSTRACT

A chuck includes a generally cylindrical body having a nose section and a tail section. A plurality of jaws are movably disposed with respect to the body to and away from the chuck&#39;s axial bore. A generally cylindrical sleeve is in driving communication with the jaws. The sleeve engages the body or the jaws by a first set of interengaged threads so that relative rotation between the first threads drives the jaws toward or away from the chuck axis. The sleeve engages the body or the jaws by a second set of interengaged threads so that relative rotation between the second threads drives the jaws toward or away from the chuck axis. The first thread set defines a first pitch so that when the jaws close, the first threads rotationally lock in the closing direction. The second thread set defines a second pitch that is higher than the first pitch so that when the jaws close, the second threads are relatively rotatable in the closing direction.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of U.S. patent applicationSer. No. 10/172,694, filed on Jun. 14, 2002, which is a continuation ofpatent application Ser. No. 09/523,426 filed Mar. 10, 2000, the entiredisclosures of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] The present invention relates generally to chucks for use withdrills or with electric or pneumatic power drivers. More particularly,the present invention relates to a chuck of the keyless type which maybe tightened or loosened by hand or by actuation of the driver motor.

[0003] Both hand and electric or pneumatic tool drivers are well-known.Although twist drills are the most common tools used with such drivers,the tools may also comprise screwdrivers, nut drivers, burrs, mountedgrinding stones, and other cutting or abrading tools. Since the toolsmay have shanks of varying diameter or may have a polygonalcross-section, the device is usually provided with a chuck that isadjustable over a relatively wide range. The chuck may be attached tothe driver by a threaded or tapered bore.

[0004] A wide variety of chucks have been developed in the art. In oneform of chuck, three jaws spaced circumferentially approximately 120°apart from each other are constrained by angularly disposed passagewaysin a body attached to the driveshaft. The chuck is configured so thatrotation of the body in one direction with respect to a constrained nutforces the jaws into or away from gripping relationship with a toolshank. Such a chuck may be keyless if it can be tightened or loosened bymanual rotation. Examples of such chucks are disclosed in U.S. Pat. Nos.5,125,673 and 5,193,824, commonly assigned to the present assignee andthe entire disclosures of which are incorporated by reference herein.Various configurations of keyless chucks are known in the art and aredesirable for a variety of applications.

[0005]FIG. 2 illustrates, in cross-section, a typical chuck jawconstruction in which each of three jaws 200 includes a back surface 202and an opposing tool-engaging surface formed by a ridge 204 disposedgenerally parallel to the chuck axis. Two generally planar side surfaces206 extend from ridge 204 to the back surface. The side surfaces on eachjaw 200 define a 120° angle δ extending through the jaw. Thus, each sidesurface on a jaw 200 is parallel to a side surface of an adjacent jaw.When the chuck is moved to its fully closed position as shown in FIG. 2,the jaw side surfaces abut each other.

[0006] Other tool-engaging surfaces are known. For example, thetool-engaging surface may be formed by an inner ridge parallel to thechuck axis and two outer ridges parallel to the inner ridge. A pair ofrespective troughs sit between the inner ridge and the outer ridges sothat the jaw's cross-section is in the shape of a W. Generally, sidesurfaces that extend from the outer ridges to the jaw's back surfacedefine a 120° angle between them through the jaw so that each sidesurface is parallel to the side surface of its adjacent jaw.

SUMMARY OF THE INVENTION

[0007] The present invention recognizes and addresses disadvantages ofprior art construction and methods.

[0008] Accordingly, it is an object of the present invention to providean improved chuck for use with a powered driver.

[0009] This and other objects are achieved by a chuck for use with amanual or powered driver having a rotatable drive shaft. The chuckincludes a generally cylindrical body having a nose section and a tailsection. The tail section is configured to rotate with the drive shaft.The nose section has an axial bore formed therein. A plurality of jawsare moveably disposed with respect to the body to and away from theaxial bore. A generally cylindrical sleeve is in driving communicationwith the jaws so that rotation of the sleeve with respect to the body ina closing direction moves the jaws toward the chuck axis and so thatrotation of the sleeve with respect to the body in an opening directionmoves the jaws away from the chuck axis. The chuck includes a first setof interengaged threads by which the sleeve engages one of the body andthe jaws so that relative rotation between the first threads drives thejaws toward or away from the chuck axis. The chuck includes a second setof interengaged threads by which the sleeve engages one of the body andthe jaws so that relative rotation between the second threads drives thejaws toward or away from the chuck axis. The first thread set defines afirst pitch so that when the jaws close, the first threads rotationallylock in the closing direction. The second thread set defines a secondpitch that is higher than the first pitch so that when the jaws close,the second threads are relatively rotatable in the closing direction.

[0010] The accompanying drawings, which are incorporated in andconstitute a part of this specification, illustrate one or moreembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A full and enabling disclosure of the present invention,including the best mode thereof directed to one of ordinary skill in theart, is set forth in the specification, which makes reference to theappended drawings, in which:

[0012]FIG. 1 is a plan view partly in section, of a chuck constructed inaccordance with an embodiment of the present invention;

[0013]FIG. 2 is a cross-sectional view of prior art chuck jaws;

[0014]FIG. 3 is a cross-sectional view of jaws for use in a chuckconstructed in accordance with an embodiment of the present invention;

[0015]FIG. 4 is a cross-sectional view of jaws for use in a chuckconstructed in accordance with an embodiment of the present invention;

[0016]FIG. 5 is a plan view, partly in section, of a chuck constructedin accordance with an embodiment of the present invention;

[0017]FIG. 6 is an exploded view of the chuck as shown in FIG. 5;

[0018]FIG. 7 is a plan view, partly in section, of a chuck in accordancewith an embodiment of the present invention;

[0019]FIG. 8 is a plan view, partly in section, of the chuck as in FIG.7;

[0020]FIG. 9 is a plan view, partly in section, of the chuck as in FIG.7;

[0021]FIG. 10 is an exploded view of the chuck as in FIG. 7;

[0022]FIG. 11 is a plan view of a thrust plate for use in the chuck asin FIG. 7;

[0023]FIG. 12 is a plan view, partly in section, of a chuck inaccordance with an embodiment of the present invention; and

[0024]FIG. 13 is an exploded view of the chuck as in FIG. 12.

[0025] Repeat use of reference characters in the present specificationand drawings is intended to represent same or analogous features orelements of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0026] Reference will now be made in detail to presently preferredembodiments of the invention, one or more examples of which areillustrated in the accompanying drawing. Each example is provided by wayof explanation of the invention, not limitation of the invention. Infact, it will be apparent to those skilled in the art that modificationsand variations can be made in the present invention without departingfrom the scope or spirit thereof. For instance, features illustrated ordescribed as part of one embodiment may be used on another embodiment toyield a still further embodiment. Thus, it is intended that the presentinvention covers such modifications and variations as come within thescope of the appended claims and their equivalents.

[0027] Referring to FIG. 1, a chuck 10 includes a front sleeve 12, anoptional rear sleeve 14, a body 16 and jaws 18. Body 16 is generallycylindrical in shape and includes a nose or forward section 20 and atail or rearward section 22. An axial bore 24 is formed in nose section20 and is somewhat larger than the largest tool shank that the chuck isdesigned to accommodate. A threaded bore 26 is formed in tail section 22and is of a standard size to mate with the drive shaft of a powered orhand driver (not shown). The bores 24 and 26 may communicate at acentral region of body 16. While a threaded bore 26 is described, suchbore may be replaced with a tapered bore of a standard size to mate witha tapered drive shaft. Furthermore, the body may be formed integrallywith the drive shaft.

[0028] A plurality of passageways 30 are formed in body 16 toaccommodate each jaw 18. Preferably, three jaws 18 are employed, andeach jaw is separated from the adjacent jaw by an arc of approximately120°. The axes of passageways 30 and jaws 18 are angled with respect tothe chuck axis 31 but intersect the axis at a common point ahead ofchuck body 16. Each jaw 18 has a tool engaging surface that is generallyparallel to the axis of axial bore 24, which is axis 31 of chuck body16. Each jaw 18 also defines threads 34 on its opposite or back surface.

[0029] Body 16 includes a thrust ring 36 which may be integral with thebody. Thrust ring 36 includes a forward face that may include a seatingsurface for engagement with the inner race of a self-containedantifriction bearing assembly 42. Bearing assembly 42 may comprise anysuitable construction, for example a bearing assembly of the typedescribed in U.S. Pat. No. 5,348,318, incorporated by reference herein.Thrust ring 36 includes a plurality of jaw guideways 50 formed aroundits circumference to permit retraction of jaws 18.

[0030] A nut 60 includes threads 62 for mating with threads 34 on jaws18 whereby when the nut is rotated with respect to the body, the jawsare advanced or retracted in the jaw passageways. Front sleeve 12includes a metal annular collar 63 that is co-molded with the sleeve andthat is pressed onto the nut so that the nut rotates with the sleeve. Itshould be understood that various sleeve and nut configurations may beemployed. For example, sleeve 12 may be pressed onto nut 60 withoutcollar 63. Furthermore, while a one-piece nut is illustrated, atwo-piece nut configuration may be used in conjunction with a collar 63where the chuck body receives a two-piece nut within an annular groove.Still further, sleeve 12 may be loosely fitted over body nose section 20and may include drive ribs that engage drive slots in the nut so thatthe front sleeve rotationally drives the nut.

[0031] Returning to FIG. 1, a nosepiece 58 is pressed onto nose section20 of body 16 to maintain nut 60 axially in position. Since sleeve 12 ispressed onto nut 60, nosepiece 58 also retains sleeve 12 in position.Nosepiece 58 defines a rear frustoconical surface 59 to allow passage ofjaws 18 rearward of body passageways 30. While nosepiece 58 is pressedonto body 16 as shown in FIG. 1, it should be appreciated that thenosepiece could also be secured by snap fit, threading or the like.Nosepiece 58 is exposed when the chuck is assembled and is preferablycoated with a non-ferrous metallic coating to prevent rust and toenhance its appearance.

[0032] Tail section 22 of body 20 can include a rear cylindrical portionhaving a knurled surface 64 thereon for receipt of rear sleeve 14. Therear sleeve may be pressed onto the knurled surface or could be retainedin place by press fit without knurling or by use of a key. It could alsobe retained by crimping, staking, riveting, threading or any othersuitable securing mechanism. Where front and rear sleeves 12 and 14 arereplaced by a single sleeve extending substantially the length of body16, a retaining disk may be pressed or otherwise retained on the tailsection to maintain the sleeve on the body in the rearward direction.

[0033] The outer circumferential surface of sleeve 12 may be knurled ormay be provided with longitudinal ribs or other protrusions to enablethe operator to grip it securely. In like manner, the circumferentialsurface of rear sleeve 14, if employed, may be knurled or ribbed ifdesired. The front and rear sleeves may be fabricated from a structuralplastic such a polycarbonate, a filled polypropylene, for exampleglass-filled polypropylene, or a blend of structural plastic materials.Other composite materials such as, for example, graphite filledpolymerics could also be suitable in certain environments. Further, thesleeves may be constructed from suitable metals, such as steel. As wouldbe appreciated by one skilled in the art, the materials from which thechuck of the present invention is fabricated may depend upon the end useof the chuck, and the above are provided by way of example only.

[0034]FIG. 3 provides a cross-sectional illustration of jaws 18 alongthe lines 3-3 as shown in FIG. 1. Each jaw includes a back surface 66and a tool-engaging surface defined by a ridge 68 parallel to chuck axis31. Each jaw includes two side surfaces 70 that extend from the jaw'stool-engaging ridge 68 to its back surface 66. Each jaw's side surfaces70 are disposed symmetrically on either side of a plane 72 that includeschuck axis 31 and the jaw's tool-engaging ridge 68. That is, plane 72evenly splits the angle between a jaw's side surfaces. Each side surfaceis generally planer. That is, a side surface may incidentally deviatefrom an ideal plane such that the side surface would not typically biteinto a tool shank.

[0035] Where chuck 10 includes three jaws, side surfaces 70 of each jaw18 define an angle δ through the chuck that is greater than 120°. Wherethe chuck includes a different number of jaws, the angle is greater than360° divided by that number. Accordingly, side surfaces 70 are notparallel to side surfaces of their adjacent jaws and do not fully abutthose side surfaces when the chuck is in a fully closed position asshown in FIG. 3.

[0036] Because opposing side surfaces 70 of adjacent jaws 18 divergefrom each other from jaw back surfaces 66 to the tool-engaging surfaces,a tool shank that is placed into the chuck bore, but that is offset fromchuck axis 31 so that it sits between opposing side surfaces, tends tobe pushed back toward the chuck center axis as the jaws close. This isparticularly advantageous in a fast-closing chuck as described below.

[0037] The magnitude of angle δ may depend on the chuck's construction.For example, chucks having a nose section axial bore within a range ofapproximately 10 millimeters in diameter to 13 millimeters in diametermay have jaws with side surfaces that define an angle δ within a rangeof 130° to 140°. In two exemplary embodiments, jaws of a chuck having a10 mm capacity define side surface angles δ of approximately 130°, andjaws of a chuck having a 13 mm capacity define angles δ of approximately136°. When the jaws of the 10 mm chuck fully close on each other, theirridges 68 define a circle of approximately 1 mm diameter. Thus, the jawsare able to securely hold tool shanks larger than 1 mm. Thecorresponding diameter for the 13 mm chuck is approximately 1.5 mm.Angle δ may vary from 130° and 140° for these type chucks, depending onthe minimum diameter tool shank the chuck must grip. Angle δ may alsovary with the chuck axial bore diameter, for example ranging from 125°to 145° for exemplary chucks slightly smaller than 10 mm in capacity andslightly larger than 13 mm in capacity, respectively.

[0038] It should be understood that various tool-engaging surfaces maybe used on the jaws. For example, referring to FIG. 4, the tool-engagingsurface of each jaw 18 includes an inner ridge 74 and two outer ridges76 disposed parallel to chuck axis 31. Each outer ridge 76 is separatedby a trough from inner ridge 74 so that the tool-engaging surfacedefines a W-shaped cross-section. As shown in FIG. 4, angle δ betweeneach pair of side surfaces 70 is greater than 120°. In still furtherembodiments, the planar side surfaces do not necessarily extend entirelyback to the jaw back surface.

[0039] It should also be understood that jaws as described herein may beused with a variety of chuck configurations. For example, referring toFIGS. 5 and 6, a chuck 110 having jaws 18 as described above withrespect to FIGS. 3 and 4 includes a front sleeve 114, an optional rearsleeve 116 and a plurality of jaws 18. A body 120 is generallycylindrical in shape and includes a nose or forward section 122 and atail or rearward section 124. An axial bore 126 is formed in the nosesection and is somewhat larger than the largest tool shank that thechuck is designed to accommodate. As should be understood in this art,body 120 may be formed from steel bar stock or any other suitablematerial.

[0040] Body 120 defines a threaded bore 128 in its tail section. Bore128 is of a standard size to mate with the drive shaft of a powered orhand driver. While a threaded bore 128 is illustrated, such bore couldbe replaced with a tapered bore of a standard size to mate with atapered drive shaft. Furthermore, tail section 124 may be formedintegrally with the drive shaft. The bores 126 and 128 may communicateat a central region 130 of body 120. Central region 130 may be formedwith a socket to accept a drive bit so that the body may be screwed ontothe spindle by the bit. Such a socket configuration is described in the'824 patent incorporated by reference above.

[0041] Body 120 also defines three passageways 132 to respectivelyaccommodate the three jaws. In a three-jaw configuration, eachpassageway, and therefore each jaw, is separated from each adjacentpassageway by an arc of approximately 120°. The longitudinal axes of thepassageways 132 and the jaws 18 are angled with respect to the chuck'slongitudinal axis 112 but intersect the chuck axis at a common pointahead of chuck body 120.

[0042] Body 120 also includes a thrust ring member 136, which in apreferred embodiment forms an integral part of the body. Although notpresently preferred, the thrust ring may be a separate component fromthe body's main portion. As shown in FIG. 5, thrust ring 136 includes aledge portion that receives a bearing assembly 142. The bearing assemblyincludes a bearing cage 144 and a pair of washers on either side of thecage. Bearing assembly 142 may comprise any suitable construction, forexample a bearing assembly of the type described in the '318 patentincorporated by reference above.

[0043] Tail section 124 can include a rear cylindrical portion having aknurled surface 156 thereon for receipt of rear sleeve 116. The rearsleeve may be pressed onto the knurled surface or could be retained inplace by press fit without knurling or by use of a key. It could also beretained by crimping, staking, riveting, threading or any other suitablemechanism. Where front and rear sleeves 114 and 116 are replaced by asingle sleeve extending substantially the length of body 120, aretaining disk may be pressed or otherwise retained on the tail sectionto maintain the sleeve on the body in the rearward direction. Thesleeves may be made from any suitable material, for example as describedabove.

[0044] Nose section 122 is beveled and is adapted to receive a nosepiece 157 for restraining front sleeve 114 from forward axial movementwith respect to the chuck body. Alternatively, a snap ring or othersuitable mechanism may be used to axially restrain the sleeve. Nosepiece 157 may be pressed onto nose section 122 or attached in any othersuitable manner. Rearward axial movement of the sleeve on the body isprevented by thrust ring 136 through bearing assembly 142.

[0045] The front sleeve's interior surface 159 defines female threads158. The threads are a modified square thread formation in an eightpitch configuration along the length of sleeve 114. It should beunderstood, however, that any suitable thread shape or formation may beemployed, for example including a modified buttress thread. Thus, thesquared interfaces between the outer surface and the back side and/orfront side of thread 158 may be replaced by a curved interface.

[0046] A nut 160 includes a male thread 162 extending about an outercircumferential surface 164. Thread 162 has the same the same pitch asthread 158 so that when thread 162 is received by thread 158, relativerotation between sleeve 114 and nut 160 moves the nut axially within thesleeve. In particular where the nut is molded, thread 162 may havesloped sides, for example at an approximately 5° slope, extending fromsurface 164 to the threads' outer diameter.

[0047] Nut 60 includes three equiangularly spaced apart slots 166extending axially through the nut and receiving respective end sections168 of jaws 18 therethrough. Each end section has a generallyrectangular cross-section that corresponds to the cross-section of itsslot 166 so that the slot slidably receives the jaw end section butprevents rotation of the jaw about the jaw's axis.

[0048] Each end section 168 defines a slot 176 extending generallyradially into the end section. The end sections extend through the slots166 so that the slots 176 are rearward of and parallel to the rear faceof nut 160.

[0049] Each slot 176 receives a respective elongated spring arm 180 thatextends inward from and generally circumferentially within a steel backring 182. Arms 180 bias their distal ends radially inward with respectto back ring 182. Thus, spring arms 180 grip the jaw end sections torestrain rotation of ring 182 about chuck axis 112 when jaws 18 arereceived in slots 132. Furthermore, arms 180 axially fix ring 182 withrespect to the jaws.

[0050] As apparent from FIGS. 5 and 6, jaws 18 are unable to passrearwardly through nut 160, and ring 182 restrains the jaws from movingin the forward axial direction with respect to the nut. Furthermore, thejaws pass through both nut slots 166 and body slots 132, therebyrotationally securing the nut with respect to the body. Since the nutcannot rotate with respect to the body, rotation of sleeve 114 withrespect to the body moves nut 160 axially with respect to chuck axis 112by the cooperation between threads 162 and 158. Depending on thesleeve's rotational direction, the nut moves axially forward or backwardon the body to move jaws 18 axially in slots 132 to an open or closedposition.

[0051] Spring arms 180 help to maintain the jaws in an aligned positionin passageways 132. It should be understood, however, that any suitablemechanism may be used to retain the jaws axially within the jawpassageways. For example, back ring 182 may be replaced by a garterspring or any other suitable retainer, such as an expandable polymercollar, that applies a radially inward force to jaw end sections 168.Alternatively, the nut may be formed with T-shaped slots or cylindricalbores instead of slots 166. Each of three equiangularly spaced T-shapedor cylindrical slots extends radially into the nut and may extendentirely through the nut. Jaw end sections 168 are formed in acorresponding T-shape or semicircle-shape so that the slots slidablyreceive the respective jaw ends. The slots allow the jaw ends to moveradially as the nut moves the jaws between open and closed positions. Adry lubricant coating may be provided on the jaw ends and/or nut slotsto facilitate this movement. The cooperation between the jaw ends andthe nut slots maintains the jaws at the proper angle with respect to thenut so that the jaws are maintained in alignment with the jawpassageways in the assembled chuck.

[0052] In still another preferred embodiment, a guide ring may bepressed onto thrust ring 136. Three equiangularly spaced prongs extendrearwardly from the ring against respective jaws 18 rearwardly of jawpassageways 132, thereby maintaining the jaws in axial alignment withthe passageways. Back ring 182, a garter spring, or a nut-slotconfiguration may be used in conjunction with the guide ring.

[0053] Rotation of sleeve 114 clockwise, when viewed from nose section122, moves nut 160 axially forward with respect to chuck axis 112,thereby moving jaws 18 to a closed position. Conversely,counterclockwise rotation of the front sleeve moves the jaws in anopening direction. A stop 192 is provided at the rear edge of thread158. When the jaws reach a fully opened position, a rear edge 194 ofthread 162 abuts stop 192. This prevents further rotation of the sleevewith respect to the nut and thereby prevents the jaws from binding inthe chuck's rear area. A similar stop 196 is provided at the front endof thread 158 to stop a forward edge 198 of thread 162 to prevent thejaws from binding in the fully closed position when there is no tool inthe chuck bore.

[0054] Thread 162 defines one turn around surface 164 of nut 160. A gapbetween thread edges 194 and 198 has an angular width greater than thewidth of stop 192. This facilitates the chuck's assembly in that the nutmay be placed directly down onto thread 158 over the stop. Rear sleeve116 then prevents the nut from disengaging from the front sleeve whenthe chuck is in a fully opened position.

[0055] Referring now to FIGS. 7 and 10, jaws 18 may also be included ina fast-closing chuck 200 having a front sleeve 214, an optional rearsleeve 216 and three jaws 18. A body 220 is generally cylindrical inshape and includes a nose or forward section 222 and a tail or rearwardsection 224. An axial bore 226 is formed in the nose section and issomewhat larger than the largest tool shank that the chuck is designedto accommodate.

[0056] Body 220 defines a threaded bore 228 in its tail section. Asnoted above, bore 228 may be a tapered bore of a standard size to matewith a tapered driveshaft. Furthermore, body 220 may be integrallyformed with the driveshaft. The bores 226 and 228 may communicate at acentral region 230 of body 220. Central region 230 may be formed with asocket to accept a drive bit so that the body may be screwed onto thespindle by the bit.

[0057] Body 220 also defines three passageways 232 to respectivelyaccommodate the three jaws 18. In a three-jaw configuration, eachpassageway, and therefore each jaw, is separated from each adjacentpassageway by an arc of approximately 120°. The longitudinal axes of thepassageways 232 and the jaws 18 are angled with respect to the chuck'slongitudinal axis 212 but intersect the chuck axis at a common pointahead of chuck body 220.

[0058] Body 220 includes a thrust ring 236, which may be integrallyformed with or separate from the body's main portion.

[0059] Tail section 224 can include a rear cylindrical portion having aknurled surface 256 thereon for receipt of rear sleeve 216. The rearsleeve may be pressed onto the knurled surface or could be retained inplace by press fit without knurling or by use of a key. It could also beretained by crimping, staking, riveting, threading or any other suitablesecuring mechanism. Where front and rear sleeves 214 and 216 arereplaced by a single sleeve extending substantially the length of body220, a retaining disk may be placed or otherwise retained on tailsection 224 to maintain the sleeve on the body in the rearwarddirection.

[0060] The outer circumferential surface of sleeve 214 may be knurled ormay be provided with longitudinal ribs or other protrusions to enablethe operator to grip it securely. In like manner, the circumferentialsurface of rear sleeve 216, if employed, may be knurled or ribbed ifdesired. The front and rear sleeves may be fabricated from a suitablematerial such as described above.

[0061] The interior surface of sleeve 214 defines three female threads258A, 258B and 258C. The threads are a square thread formation. Nut 260includes three male threads 262A, 262B and 262C that are received inthreads 258A, 258B and 258C, respectively. As described in more detailbelow, nut 260 is rotationally fixed to body 220. Accordingly, rotationof sleeve 214 about the body drives nut 260 axially within the sleeve.Sleeve threads 258A, 258B and 258C and nut threads 262A, 262B and 262Cprovide a one pitch configuration along the length of sleeve 214 in thatone complete relative rotation between sleeve 214 and nut 260 moves thenut approximately one inch axially within the sleeve.

[0062] Three female threads and three male threads are used to permit arelatively narrow nut. That is, it is preferable that the nut threadextends substantially entirely about the nut's outer circumference sothat the nut remains balanced during the chuck's operation. Where asingle female/male thread pair is used, the male thread about the nut'scircumference would require that the nut be longer in the axialdirection than where the three-thread configuration is used.Nevertheless, it should be understood that the present inventionencompasses other thread configurations, for example one-thread,two-thread and four-thread arrangements.

[0063] Nut 260 is slidably received over a body portion 264 of a thrustplate 266. A flange 268 extends radially outward from plate body 264 anddefines a ledge 270 upon which a bearing assembly 272 is received.Bearing assembly 272 includes a first race 274 having recesses 276defined about the radially outward edge of its rearward face. Anopposite race 278 includes a shroud 280 extending axially forwardtherefrom. The shroud defines a plurality of spring arms 282 biasedaxially forward toward washer 274 so that tabs 284 defined at the distalends of arms 282 engage respective recesses 276. When, as describedbelow, nut 262 rotates with respect to thrust plate 266, frictionalforces between washer 274 and thrust plate 266 and between washer 278and nut 260 overcome the link between washers 278 and 274 provided bythe engagement of tabs 284 in recesses 276. Thus, spring arms 282 aredeflected so that each tab 284 moves out of its recess 276 and into thenext recess. Continued rotation of nut 260 with respect to the thrustplate moves tabs 284 in and out of successive recesses, creating aclicking sound notifying the user that the chuck is approaching a fullyclosed position.

[0064] In another embodiment, washer 274 includes radially alignedrecesses in its rearward face so that each of bearing balls 286 isreceived in a respective recess. Spring arms 282 are omitted. Whenrelative rotation between nut 260 and thrust plate 266 causes relativerotation between washers 278 and 274, each ball 286 rolls out of itsrecess into the next recess. Continued rotation continues movement ofthe balls through successive recesses, causing a clicking sound thatnotifies the operator that the chuck is approaching a fully tightenedposition as described below.

[0065] Nut 260 is held rotationally with respect to thrust plate 266 bya torsion spring 290. Torsion spring 290 includes ends 292 and 294 thatare received in opposing holes 296 and 298, respectively.

[0066] A detent ball 300 is received in any of three depressions 302 inthrust plate body section 264, depending on the holes 296 and 298 thatreceive the torsion spring ends, so that ball 300 is received in agroove 304 in the inner diameter of nut 260. Ball 300 provides a stopagainst the edges of groove 304, thereby limiting the range over whichnut 260 can rotate with respect to the thrust plate. During normaloperation before the chuck closes onto a tool shank, ball 300 preferablysits against a side of groove 304 so that, when the chuck closes onto atool shank, rotation of nut 260 is permitted through the full angularwidth of groove 304. It should be understood that the length of groove304 may be modified as desired to permit a greater degree of rotationalmovement of nut 260 with respect to thrust plate 266. For example, inone preferred embodiment, the angular width of groove 304 isapproximately 240°.

[0067] Referring also to FIG. 11, thrust plate 266 includes threeequiangularly spaced apart radial slots 306 that are generally T-shaped.An end portion 308 of each jaw 18 is formed in a cooperating T-shape sothat slots 306 slidably receive the respective jaws. The slots allow thejaw ends to move radially as the thrust plate moves the jaws betweenopen and closed positions. A dry lubricant coating may be provided onthe jaw ends and/or slots 306 to facilitate this movement. Thecooperation between the jaw ends and slots 306 maintains the jaws at theproper angle with respect to the thrust plate so that the jaws aremaintained in alignment in the jaw passageways in the assembled chuck.Slots 306 may also be cylindrical in shape, for example as shown in theembodiment illustrated in FIG. 13, and each jaw end section 308 may beformed in a cooperating semi-circular shape so that slots 306 receivethe respective jaws.

[0068] Referring again to FIGS. 7 and 10, body nose section 222 includesthreads 310 that engage threads 312 at a front end of sleeve 214. In theillustrated embodiment, threads 312 are formed about the inner surfaceof a metallic insert 314. The outer surface of insert 314 is knurled at316 and is received at the forward end of sleeve 214 in a press fit at318. Threads 310 and 312 form a secondary threaded tightening mechanismhaving a higher pitch than the primary threaded tightening mechanismformed between threads 258 and 262.

[0069] Because jaws 18 are received in jaw passageways 232, the jaws areconstrained from rotation about the chuck's axis. The receipt of jawends 308 by slots 306 rotationally holds thrust plate 266 with respectto chuck body 220. When the chuck is between its fully opened positionand a fully closed position in which the chuck jaws are closed on eachother or on a tool, friction between nut threads 262 and threads 258 isnot sufficient to rotate nut 260 against the force of torsion spring290. Thus, in operation and referring to FIG. 8, rotation of sleeve 214in a clockwise direction (when viewed from the front of chuck 200) movesnut 260 axially forward with respect to the sleeve as indicated at arrow318. Nut 260 presses forward against thrust plate 266 through bearingassembly 272, moving the bearing assembly forward with respect to body220. Thrust plate 266, in turn, drives jaws 18 axially forward in theirpassageways 232, thereby moving the chuck toward a closed position.Rotation of sleeve 214 in the opposite direction moves nut 260 axiallyrearward with respect to the sleeve, as indicated by arrow 320. Sincenut 260 is restrained in the axially rearward direction with respect tothrust plate 266 by a snap ring 314, the nut carries thrust plate 266and jaws 18 axially rearward toward the chuck's open position.Accordingly, in both the opening and the closing directions, sleeve 214axially drives the jaws through relative rotation between the sleeve andthe nut. That is, the sleeve drivingly engages the jaws through threads258 and 262.

[0070] Sleeve threads 312 also rotate about body threads 310 as sleeve214 rotates. Threads 312 are in the opposite direction of thread 258,and threads 310 are in the opposite direction of thread 262. Thus, assleeve 214 rotates in the closing (clockwise) direction, sleeve 214moves on threads 310 axially forward with respect to the body indirection 318. When the sleeve is rotated in the opposite direction, thesleeve moves rearwardly on threads 310 in direction 320.

[0071] Accordingly, when sleeve 214 is rotated in the closing direction,nut 260 moves forward in direction 318 within the sleeve, while sleeve214 simultaneously moves forward in direction 318 with respect to thebody on body threads 310. Because threads 312 and 310 define a higherpitch than threads 258 and 262, nut 260 moves forward with respect tothe sleeve faster than sleeve 214 moves forward with respect to thebody. For example, in the one-pitch configuration illustrated in FIG. 8,approximately two full rotations of sleeve 214 are required to move nut260 from its rearwardmost position with respect to the sleeve to itsforwardmost position as shown in FIG. 7. In these two turns, sleeve 214moves only 1/16th inch forward on body 220.

[0072] Referring now to FIG. 9, when sleeve 214 is rotated such thatjaws 18 close onto a tool shank 322, jaws 18, thrust plate 266 and nut260 are unable to continue their forward axial movement. Accordingly,continued rotation of sleeve 214 tightens thread 258 against thread 262.The frictional force between threads 258 and 262 overcomes theresistance of torsion spring 290, and nut 260 rotates with sleeve 214with respect to the thrust plate and the chuck body. This rotationcarries sleeve 214 forward on body threads 310, thereby pressing nut 260forward against thrust plate 266 through bearing assembly 272. Thethrust plate, in turn, further presses jaws 18 down onto tool shank 322.As discussed above, rotation between nut 260 and thrust plate 266produces a clicking sound from bearing 272 and is limited by the angularwidth of groove 304 in nut 260 (FIG. 10).

[0073] As threads 312 tighten onto threads 310, the forward force ofsleeve 214 against nut 260 further tightens threads 258 and 262. Whenthe operator releases sleeve 214, the sleeve and nut remain in theirtightened rotational positions with respect to the chuck body.

[0074] Accordingly, chuck 200 includes a primary tightening mechanismand a secondary tightening mechanism. The primary tightening mechanism,threads 258 and 262, rapidly moves jaws 18 radially toward and away fromthe chuck axis. The low pitch of these threads, however, provides arelatively low mechanical advantage as the jaws tighten onto the tool. Ahigher advantage is supplied by the higher-pitch threads 312 and 310,and it is this secondary tightening that finally tightens jaws 18 ontothe tool shank.

[0075] As indicated above, the primary thread is a one-pitch thread, andthe secondary thread is a 32-pitch thread. It should be understood,however, that the pitch values, and the pitch ratio, can vary assuitable for the needs and construction of a given chuck. Generally, theprimary pitch is such that the chuck opens and closes rapidly androtationally locks in the closing direction when the jaws close on eachother or a tool. That is, when the jaws close, a human operator isunable to relatively rotate the threads in the closing direction. Thesecondary thread pitch is such that when the jaws close, the threadsprovide sufficient mechanical advantage that the operator is able tocontinue relative rotation in the closing direction.

[0076] To open the chuck, the operator rotates sleeve 214 in the openingdirection. Sleeve 214 moves axially rearward in direction 320 withrespect to chuck body 220 on threads 310. This releases the wedgebetween threads 258 and 262, thereby allowing torsion spring 290 tocarry the nut back to its original rotational position with respect tothrust plate 266 and the chuck body. Continued rotation of sleeve 214moves the nut, thrust plate and jaws axially rearward and away from thetool shank.

[0077]FIGS. 12 and 13 illustrate a further embodiment of chuck 200. Thechuck is a single-sleeve chuck, and the outer surface of sleeve 214extends to the rear of chuck body 220. A cover plate 324 is axiallyretained on body 220 by snap rings 326 and 328. Sleeve threads 312 andbody threads 310 (FIG. 7) are replaced by threads 330 on the innercircumferential surface of nut 260 and threads 332 on the outercircumferential surface of the body portion of thrust plate 266. Bearingassembly 272 is disposed between sleeve 214 and body thrust ring 236. Asnap ring 334 holds sleeve 214 in the axially forward direction on body220.

[0078] In this embodiment, threads 258 and 262 are in an eight-pitchconfiguration. Nut 260 defines two threads 262A and 262B about its outercircumference. The inner surface of sleeve 214 defines two threads 258Aand 258B that receive threads 262A and 262B, respectively. Threads 330and 332 define a 32-pitch.

[0079] Friction between threads 258 and 262 is normally insufficient toovercome the force of torsion spring 290 keeping the nut and thrustplate rotationally together. Accordingly, when chuck 200 is between afully opened and fully closed position, rotation of sleeve 214 in aclockwise direction (when viewed from the front of chuck 200) drives nut260 axially forward with respect to sleeve 214 and body 220 in direction318. Nut 260 is axially held to thrust plate 268 by threads 330 and 332.Thus, movement of nut 260 in direction 318 also moves thrust plate 266,thereby moving jaws 18 in passageways 232 toward the chuck axis.

[0080] When the jaws clamp onto a tool, jaws 18 exert a rearward forceto sleeve 214 through thrust plate 266 and nut 260. Continued rotationof sleeve 214 wedges threads 258 and 262. Although a wedge also developsbetween threads 330 and 332, the rotational force applied to the nut bysleeve 214 is greater than the resistance provided by threads 330 and332, due to the much lower pitch of threads 258 and 262. The rotationalforce also overcomes the resistance of spring 290 (about 5 to 10inch-lbs). Thus, nut 260 begins rotating with the sleeve on threads 332against the spring.

[0081] Threads 330 have the same orientation as threads 258, and threads332 have the same orientation as threads 262. Thus, rotation of nut 260with sleeve 214 in the closing direction rotates the nut on threads 332so that the nut and thrust plate move axially apart from each other.Since bearing assembly 272 and the body thrust ring prevent the sleeveand nut from moving rearwardly, this rotation forces thrust plate 266axially forward, thereby further pressing jaws 18 down onto the toolshank. Continued rotation wedges threads 330 and 332. This wedgeovercomes the force of torsion spring 290 so that, when an operatorreleases the sleeve, the chuck remains in the fully tightened position.

[0082] To open the chuck, the operator rotates sleeve 214 in the opening(counterclockwise) direction. This rotates nut 260 in the openingdirection with respect to thrust plate 266, moving thrust plate 266, andtherefore jaws 18, axially away from the tool shank. When the nutreturns to its original rotational position on the thrust plate, furtherrotation of sleeve 214 moves the nut, thrust plate and jaws axiallyrearward, away from the tool.

[0083] It should be understood that various jaw configurations,including the arrangement illustrated in FIG. 2, may be employed withthe chucks of FIGS. 7-13.

[0084] While one or more preferred embodiments of the invention havebeen described above, it should be understood that any and allequivalent realizations of the present invention are included within thescope and spirit thereof. The embodiments depicted are presented by wayof example only and are not intended as limitations upon the presentinvention. For example, while the sleeve in the embodiments illustratedin FIGS. 7-13 forms an exterior surface of the chuck, a chuck inaccordance with the present invention could include a sleeve that is aninterior component that rotates with respect to the body to drive thejaws. Thus, it should be understood by those of ordinary skill in thisart that the present invention is not limited to these embodiments sincemodifications can be made. Therefore, it is contemplated that any andall such embodiments are included in the present invention as may fallwithin the literal and equivalent scope of the appended claims.

What is claimed is:
 1. A chuck for use with a manual or powered driverhaving a rotatable drive shaft, said chuck comprising: a. a generallycylindrical body having a nose section and a tail section configured torotate with said drive shaft, said nose section having an axial boreformed therein and a plurality of angularly disposed passageways formedtherethrough and intersecting said axial bore; b. an inner sleeve havinga central bore and a threaded outer circumferential surface, whereinsaid body is received within said central bore; c. a plurality of jawsslidably received in respective said angularly disposed passageways,each of said jaws having a jaw face formed on one side thereof; d. anannular nut in driving engagement with said plurality of jaws, whereinsaid annular nut defines a threaded interior surface and is receivedabout and threadedly engages said outer surface of said inner sleeve sothat relative rotation between said inner sleeve and said annular nutmoves said annular nut and said inner sleeve axially with respect toeach other; e. a spring disposed between said annular nut and said innersleeve, said spring biasing against relative rotation between saidannular nut and said inner sleeve; and f. an outer gripping sleeve,wherein said outer gripping sleeve is disposed rotatably about saidannular nut.
 2. The chuck as in claim 1, wherein said nut threadedlyengages said outer gripping sleeve.
 3. The chuck as in claim 1, whereinsaid jaws are axially fixed to said inner sleeve.
 4. The chuck as inclaim 1, wherein said outer gripping sleeve is rotatable with respect tosaid inner sleeve.
 5. The chuck as in claim 1, wherein said outergripping sleeve extends rearwardly even with a back edge of said tailsection.